By Liz MacKenzie
“…in a society which urges the reuse of items as small as pop bottles, tin cans and grocery bags (to avoid sending same to landfill), one would expect efforts to reuse items as large as buildings.”
(M. Denhez, OMB Decision, Nov 18, 2014)
In Lowertown, we have come to accept that building owners have the right to demolish just about any building. We have also come to accept that laxness of building-standard enforcement leads to “demolition by neglect”, causing, for instance, the loss of 269, 277, 285, and 291 King Edward Avenue and the appalling eyesore at Murray and Cumberland that was once Our Lady’s School.
The wish to get rid of an inconvenient heritage building such as the historic row at 316–324 Bruyère St. and the Union du Canada at 325 Dalhousie (now the Andaz Hotel) has also led to demolition.
Watching huge machines smash buildings like toys can be mesmerizing, but do we consider the rubble and other construction waste as it is hauled “away” by an army of trucks. Of course, as with most other things, there is no “away”. The disposal of construction waste is big business and more and more the environmental costs of demolition and disposal are being scrutinized.
City official are quick to say that the Ontario Ministry of the Environment, Conservation and Parks governs the management of construction waste: it is not OUR problem. However, it is the municipality that grants the demolition permits with no thought about the environmental impacts.
The environmental cost of disposal and the cultural loss of traditional, energy-saving building materials and historic construction details are largely ignored. Sending tons of material to the landfill is not weighed against the economies of repurposing or rehabilitation, but accepted as routine. And who is looking at the environmental cost of the replacement buildings?
When a building is demolished, some materials such as concrete, drywall and metal may be sorted on site and recycled. However, the energy used to crush, melt or repurpose recycling material carries a significant environmental burden. In addition, older building materials such as massive timbers, craftsmanship details or decorative elements are seldom salvaged. Added to the cost is “embodied energy”, a term that we will hear more and more. Embodied energy is the energy that was used in the original construction. It includes the energy used to manufacture and transport all the materials and the construction labour.
In addressing the issue of the demolition of older buildings with inherent embodied energy and energy-saving elements, The Technical Committee on Sustainable Preservation of the Association of Preservation Technology International notes: “…it is increasingly critical to account for the environmental impacts of every stage of a building’s life cycle. This is particularly true for historic and existing buildings ….”Catherine Naismith, Past President of the Architectural Conservancy of Ontario in her 2008 paper, “Waste Not Want Not–Buildings are Not Garbage” provides a glimpse at the environmental costs of demolition and building. She says, “Depending on the study quoted, between 20 and 35 per cent of landfill is building waste. According to statistics gathered by the Heritage Canada Foundation, construction accounts for 50 per cent of the natural resources we consume, and 10 to 30 per cent of greenhouse-gas emissions are from the production and transportation of building materials and demolition waste.
Creative Deconstruction instead of feeding urban landfill is advocated by Carleton University professor Susan Ross. Deconstruction slows down demolition so that all materials can be reclaimed. Ideally, these materials would be reused on the building site, but could be saved for a use later. Ross suggests that when the need to conserve resources is better recognized, existing buildings will be seen as urban mines, a valuable source of materials for new construction.
Clearly, there is no escaping the prominently accepted international mantra: “The most environmental building is the one that is already built.”